The purpose of this project is to collect families and individuals with inherited ataxia and other movement disorders for genetic and clinical studies, and to identify new genes by using the techniques of linkage analysis, positional cloning and allelic association studies. Analysis of our families has identified a novel type of dominantly inherited ataxia that has phenotypic features resembling Parkinson's disease and multiple sclerosis, a genetic locus for pure familial essential tremor (FET) and an allelic association between the tau gene and progressive supranuclear palsy. The expansion of trinucleotide repeats in the coding region of at least four types of dominantly inherited ataxia and the presence of anticipation (earlier symptom onset in succeeding family generations and increased disease severity) in families with ataxia and tremor may indicate a common genetic and physiologic mechanism in these disorders. Progress has been made towards testing candidate regions for repetitive sequences and gene mutations that may cause these disorders.